CN1613215B

CN1613215B - Termination unit for digital subscriber line system and method through system communication

Info

Publication number: CN1613215B
Application number: CN028270126A
Authority: CN
Inventors: J·奥利弗; C·埃文森
Original assignee: ADC DSL Systems Inc
Current assignee: Adcdsl; Commscope DSL Systems LLC
Priority date: 2001-11-09
Filing date: 2002-11-08
Publication date: 2013-12-25
Anticipated expiration: 2022-11-08
Also published as: EP1454443A4; US20030091061A1; WO2003041316A1; US7526002B2; MXPA04004402A; EP1454443A1; EP1454443B1; CN1613215A; US20060233188A1; US7088742B2

Abstract

Line termination units 110 having dual ports 112, 114 for accepting communication traffic of two different types facilitate the concurrent transmission of voice traffic, serial data traffic and packetized data traffic across a telecommunication transport system 100, such as a DSL digital subscriber line system 130. The bandwidth of the telecommunication transport system 100 is allocated between the differing traffic types to permit the full utilization of the available bandwidth.

Description

For the terminal unit of digital line system and by the method for system communication

The technical field of invention

The present invention relates generally to field of telecommunications, especially relates to the equipment and the method that promote to send by single IEC interexchange carrier a plurality of communication protocols simultaneously.

Background of invention

Some communication transportation protocols have been defined by large span and have transmitted voice and/or data service.Comprise for two examples of agreement that transmit (PCM) speech business of traditional pulse code modulation and packing data business time division multiplexing (TDM) agreement that is commonly referred to T1 (U.S.) and E1 (Europe).These two agreements have many similarities, but payload speed about them separately but has remarkable difference.The T1 business has the 1544Kbps bit rate that is divided into 24 time slots (or channel), and each time slot is 64Kbps; And the E1 business has the 2048Kbps bit rate that is divided into 32 time slots, each time slot is 64Kbps.A standard formed of voice-and-data business is G.shdsl (ITU G.991.2) standard of SHDSL (single-pair high-bit-rate digital subscriber line) data link or span, its bit rate can be up to 2304Kbps, or perhaps 36 time slots altogether of each time slot 64Kbps.

Along with the progress of telecommunication technology, promoted transmission rate faster.Yet state-of-the-art technology usually can be by round Realization.So, in telecommunication transport system, the communication from the sending node to the receiving node may cover different technologies.Interface between variety of protocol can cause waste bandwidth.For example, if got involved respectively between two T1 spans or two E1 spans, a SHDSL span will be restricted to 1544Kbps or 2048Kbps, and this causes waste that may bandwidth.

For above-mentioned reasons and those skilled in the art described below reading and understanding the other reasons that this detailed description postscript will be appreciated that, in the art need to be for increasing replacement equipment and the method for the bandwidth usage of telecommunications span.

Summary

At this, LTU Line Termination Unit is described to have for accepting the dual-port of two kinds of dissimilar communication services.Each embodiment sends when having promoted by the speech business of a telecommunication transport system such as DSL (digital subscriber line) system, serial data business and packing data business.Distribute the bandwidth of telecommunication transport system between different service types, to allow to utilize fully available bandwidth.

For an embodiment, the invention provides the terminal unit of a use in digital line system.Described terminal unit comprises the second communication interface that is suitable for receiving the first communication interface of the first business with certain bandwidth and is suitable for receiving the second business that is different from the first business.Described terminal unit also comprises for being coupled to the third communication interface of digital subscriber line.Described terminal unit is suitable for the first business received at the first communication interface place and the second combinations of services received at the second communication interface, thereby produces a composite service, and described composite service is offered to third communication interface.The composite service bandwidth is more than or equal to the bandwidth of the first business.

For another embodiment, the invention provides the terminal unit of a use in digital line system.Described terminal unit comprises the first communication interface that is suitable for receiving the first business with first timeslot number, and each time slot is corresponding to an incremental bit rate, wherein, for the timeslot number (N1) of payload, is less than or equal to the first timeslot number.Described terminal unit also comprises the second communication interface that is suitable for second business that receives, and wherein, the second service bit rate equals certain times (N2) of described incremental bit rate.Described terminal unit also comprises a third communication interface, and for being coupled to digital subscriber line and, for the composite service with second timeslot number is provided, each time slot is corresponding to described incremental bit rate, wherein, the second timeslot number is more than or equal to N1+N2.Described terminal unit is suitable for the time slot to the first of composite service the time slot mapping of the first business.Described terminal unit also is suitable for the second business is mapped to the time slot of the second portion of composite service.

For another embodiment, the invention provides a method of communicating by letter by digital line system.Described method comprises receiving to have the first business of certain bandwidth and receive the second business that is different from the first business simultaneously.The method also comprises the data of the data of the first business and the second business is combined to generate a composite service, and composite service offered to the digital subscriber line of digital line system.

For another embodiment, the invention provides a method of communicating by letter by digital line system.Described method comprises the first business with first timeslot number that receives, and each time slot is corresponding to an incremental bit rate, wherein, for the timeslot number (N1) of payload, is less than or equal to the first timeslot number.The method also comprises: receive the second business, wherein, the bit rate of the second business equals certain times (N2) of described incremental bit rate; And the first business and the second combinations of services are generated to the composite service with second timeslot number.Each time slot of this composite service is more than or equal to N1+N2 corresponding to described incremental bit rate and the second timeslot number.The method also comprises the time slot to the first of composite service the time slot mapping of the first business, and the second business is mapped to the time slot of the second portion of composite service.

The other embodiment of the present invention comprises equipment and the method for different range.

The accompanying drawing summary

Fig. 1 is the block schematic according to the telecommunication transport system of the embodiment of the present invention.

Fig. 2 is the block schematic according to the LTU Line Termination Unit of the embodiment of the present invention.

Fig. 3 is the block schematic according to the synchronizer of the embodiment of the present invention.

Fig. 4 A-4F has described the example time slot allocation according to the embodiment of the present invention.

Describe in detail

In following the present embodiment describes in detail, accompanying drawing is carried out to reference, accompanying drawing forms the part of specification, and illustrates illustratively and can put into practice specific embodiment of the present invention therein.These embodiment are enough described in detail so that those skilled in the art can put into practice the present invention, and should be appreciated that, can utilize other embodiment, and can make the change of process, electric or machinery and do not depart from scope of the present invention.Therefore, do not wish following detailed description to be considered to restrictive, scope of the present invention is only determined by appending claims and equivalents thereof.

Each embodiment sends when promoting by the speech business of the telecommunication transport system such as DSL (digital subscriber line) system, serial data business and packing data business.Distribute the bandwidth of telecommunication transport system between different service types, to allow to utilize fully available bandwidth.

Fig. 1 is the block schematic according to the telecommunication transport system 100 of the embodiment of the present invention.System 100 comprises by first node 110 and the Section Point 120 of span 130 couplings.Span 130 is a digital subscriber line (DSL) spans.For another one embodiment, this DSL span is single-pair high-bit-rate digital subscriber line (SHDSL) span.This kind of span comprises a pair of or two strand copper cash usually.First node 110 can be a LTU Line Termination Unit (LTU) that is positioned at telecommunication supplier central office (CO), and Section Point 120 can be a network temination unit (NTU) that is positioned at subscriber station, it arrives subscriber terminal equipment (CPE) for interface.LTU is main equipment normally, controls and monitor other unit such as NTU.

Although two

nodes

110 and 120 all are suitable for two-way communication usually, will using first node 110 as transmitting apparatus and Section Point 120 is discussed Fig. 1 as receiving equipment, note: both sides role can put upside down and two-way communication can occur simultaneously.

First node 110 is used suitable communication protocol to pass through span 130 transmission information to Section Point 120.For an embodiment, span 130 is to use the SHDSL span of G.shds1 standard.Business on span 130 has by the defined bandwidth of its communication protocol or Available Bit Rate.Continue the G.shds1 example, as now defined, its maximum bandwidth is 2304Kbps.As previously mentioned, this business is divided into 36 time slots, each time slot 64Kbps.The incremental bit rate that the actual bandwidth of span 130 is multiplied by each time slot by utilized timeslot number determines, this incremental bit rate is 64Kbps in this example.

The transmission information that first node 110 receives from a plurality of communication interfaces.The first communication interface 112 is coupled to receive the communication service of the first kind, such as pulse code modulation (PCM) speech business and/or packing data business.The bandwidth of this first business is less than the maximum bandwidth of span 130.For example, the first communication interface 112 can be a G.703/704 interface, the E1 business that it is coupled to receive as present defined maximum bandwidth is 2048Kbps.This type of E1 business is divided into 32 time slots, and each time slot incremental bit rate is 64Kbps.

Certain timeslot number (N1) of the first business can be used to application data or payload.Can be from zero (one not be used interface) to available bandwidth time slot sum for the timeslot number scope of payload, and be that the user is definable.Use the E1 business as an example, the time slot between 0 and 32 can be used to payload.As current definition, unless N1 is 32, unless each time slot is used to payload, otherwise the first time slot of E1 business (time slot 0) is left framing information for.In addition, unless N1 is more than or equal to 31, otherwise the 17 time slot (time slot 16) of E1 business is left signaling information for.The time slot that payload is utilized can be continuous, does not still require so and does.For example, utilize the E1 business of 11 time slots for payload, payload can be arranged in time slot 1-11.Alternately, the payload time slot can be discrete, such as time slot 4-8,13-15 and 17-19.

Second communication interface 114 is coupled to receive the communication service of the Second Type different from the first kind.For an embodiment, second communication interface 114 is serial data ports that coupling receives serial data.For another one embodiment, second communication interface 114 is Nx64Kbps interfaces, and it is coupled to receive the serial data that bandwidth is certain times (N2) of an incremental bit rate (being 64Kbps in this example).

Following discussion will relate to the embodiment of a circuit, as shown in Figure 2, terminal unit 200 have the E1 interface as the first communication interface 212 and serial data port interface as second communication interface 214.Terminal unit 200 is suitable for being coupled to DSL.For an embodiment, terminal unit 200 is adapted to pass through as a SHSDSL interface of third communication interface 216 and is coupled to SHDSL.

E1 interface 212 provides the bidirectional digital interface of a 2048Kbps for the user's application data as the PCM data flow.For an embodiment, it comprises an E1 framer and line interface unit (LIU) 218 and protection and insulator chain 220.E1 interface 212 can provide following control:

1) according to line coding and the decoding of HDB3.

2) received frame is synchronous: framing not, G.704 (FAS), CRC-4, CAS multiframe.

3) time slot 0 (FAS) regeneration or transparent transmission.

4) framing at the regeneration selected of CRC-4 data and output data place.

5) monitoring of incoming call CRC4 mistake, bipolarity upset and E-bit.

6) LOS, LFA, RAI, ais alarm indication

7), in response to alarm, CRC4 mistake, produce A bit, E bit.

8) send all frame data (AIS) that do not become.

9) whereabouts interface and away from the diagnosis loopback of interface.

10) programmable channel blanking and the idle code pattern about exporting.

In RX path, the incoming call data at E1 interface 212 places can be not framing (being complete 2048Kbps) or according to G.704 with the 64Kbps channel (8 bit time slots) of 32 separation by framing, and mutual frame is aimed at (FAS), non-frame alignment word (NFAS) is positioned at time slot 0.Unless the user selects 31 time slots to be assigned to e1 port, otherwise time slot 16 is left network common signal channel (CCS) or channel associated signaling (CAS) for, and will always with the structuring application mode, be shone upon pellucidly.

Serial data port interface 214 provide one V.35, V.36 the Nx64Kbps bidirectional interface of (X.21 option), RS-530 or other similar standards (this interface provides certain bandwidth, described bandwidth is certain times (N2) of 64Kbps incremental bit rate), so so that N2 scope from 0 to 36.Firmware can be monitored therewith interface related control signal, makes this signal effectively and participate in loopback.

Terminal unit 200 also comprises a synchronizer 222.The synchronous E1 of this synchronizer 222 and serial data stream, be presented to SHDSL interface 216 to them.Synchronizer 222 may be implemented as a field programmable gate array (FPGA), ASIC(Application Specific Integrated Circuit) (ASIC) chip or other control logic pieces.

Terminal unit 200 also comprises a SHDSL chipset 224, and this chipset is used for coming the synchronous PCM data flow of self-synchronous device 222 to be mapped in the SHDSL frame, and for this frame being provided to SHDSL interface 216 to export by the SHDSL span.On receive direction, SHDSL chipset 224 using data as PCM and narrow band data stream be provided to synchronizer 222.Synchronizer 222 and SHDSL chipset 224 can be discrete components as shown in Figure 2, or their function can be combined in single processor piece.

For an embodiment, SHDSL chipset 224 is to locate the CX28975SHDSL chipset obtained from Minds peed technology (Newport Beach, California, the U.S.).This chipset has two ports.The first port is called as the PCM port.The second port is called as narrow band port.If the lock-out pulse on narrow band port (lock-out pulse or framing pulse) is synchronizeed with the PCM port, can make two ports operate simultaneously.For Minds peed chipset, to clock cycle of PCM port, be many times of 125 microseconds, be generally 2ms or 6ms, and to the clock cycle of narrow band port be 6ms.For accurate synchronous, (for example, in 100 microseconds) generates the lock-out pulse relevant to narrow band port from the lock-out pulse of PCM port.In the U.S. Patent application sequence No. (agent's document No.100.345US01) that this process is " Multiple Dataport C1ock Synchronization " (a plurality of FPDP clock synchronous) at title, be described, this application is commonly assigned and is being hereby incorporated by reference.The lock-out pulse relevant to narrow band port further is broadened or shortens to a narrow band port clock cycle width.

Synchronizer 222 and SHDSL chipset 224 can provide following function: the combination table of 1) according to the application model of expectation, programming and sending mapping, routing table, reception mapping and comprise the FIFO water level.

2) control frame or multiframe are synchronous.

3) SHDSL line speed and frame length are set

4) SHDSL link acquisition and maintenance

5) sending and receiving EOC message.

6) monitoring SHDSL state: signal to noise ratio, loop attenuation, CRC6 mistake, Far end block error (FEBE) and remote alarm.

Data from E1 interface 212 are passed through synchronizer 222 and are fed to SHDSL chipset 224 at first input end (or PCM input (Fig. 2 is not shown)) with identical 2048Kbps bit rate.Serial data port data (it can have the Nx64k speed of part) are through synchronizer 222 and be fed to SHDSL chipset 224 at the second input or arrowband input (Fig. 2 is not shown).SHDSL chipset 224 buffer memory PCM and narrow band datas, then combine data into as single serial data stream to transmit for passing through the SHDSL span.Preferably: up to all time slots of E1 business of available SHDSL payload timeslot number by Continuous Mappings on single SHDSL span.

Fig. 3 is the block schematic according to the synchronizer 222 of the embodiment of the present invention.Only have those parts of the synchronizer 222 relevant with the interface of SHDSL chipset 224 to be described.

Except the clock signal DSL_TPCLK or master clock that are provided by main time selection circuit, lead to the PCM port 335 of SHDSL chipset 224 to the interface 330 of E1 framer and LIU218.

Interface 340 to serial data port interface 214 is passed to the narrow band port 345 of SHDSL chipset 224 by clock and data polarity controll block 350.For an embodiment, via the TNBCLK signal, to be phase-locked to the timing of the Nx64K increment generation narrow band port 345 on the DSL_TPCLK signal.The TNBCLK signal is also through oversampling clock and data polarity controll block 350, and the transmission that is used to drive serial data port (DP_ST) signal regularly.SHDSL narrow-band reception clock (RNBCLK) and data (RNBDAT) are delivered to receive clock (RT) and the data (RD) of serial data port through oversampling clock and data polarity controll block 350.From the transmission data (DP_SD) of serial data port, drive arrowband to send data (TNBDAT).

Serial data port can be accepted data with the speed of Nx64K.This is to say: any times of 64KHz until 2304KHz can be used as input clock speed.The FPDP input clock must be locked into the DSL_TPCLK signal, in order to guarantee I/O FIFO nonoverload operation or underrun during steady state operation, vice versa.When Nx64KHz FPDP transmission timer clock (DP_TT) is selected as the timing base of system, a clock synthesizer circuit is used to produce the fixedly 2048KHz benchmark as DSL_TPCLK output.When a source except the DP_TT clock is selected as the timing benchmark, the clock synthesizer circuit is used to produce a Nx64KHz DP_ST clock source, and serial data port must be used the timing base of this clock source as it.

For an embodiment, obtain the lock-out pulse TNBSYNC of narrow band port 345 from the reception multiframe lock-out pulse E1_RMSYNC from E1 interface 330.The E1_RMSYNC lock-out pulse is a 2ms pulse that was approximately for 500 nanoseconds the duration.For the required 6ms lock-out pulse of the narrow band port that produces the Mindspeed chipset, at first use fixing divider 360 the E1_RMSYNC lock-out pulse except in order to produce a 6ms lock-out pulse.The 6ms lock-out pulse of resulting centre will still have the duration same with E1_RMSYNC pulsion phase now.The intermediate sync pulse of this 6ms duration can optionally output to DSL_TPMSYNC signal (not shown).Then utilize programmable divider 370 that intermediate sync pulse is widened or shortened, there is 6ms interval and duration with generation and be substantially equal to the lock-out pulse TNBSYNC of the clock interval of clock signal TNBCLK.Arrowband lock-out pulse TNBSYNC should with the E1_RMSYNC lock-out pulse phase alignment by E1 framer 218 output.Arrowband lock-out pulse TNBSYNC should occur in the 0-100 microsecond after the E1_RMSYNC lock-out pulse.Because the frequency of arrowband clock TNBCLK can change, so the numerical value be written in the division circuit of programmable divider 370 also must change.A reciprocal counter is used to produce programmable divider 370.The equation that the computing counter heavy duty enters numerical value is: heavy duty is worth=converts to hex (6ms*TNBCLK (freq)-2).

Following form provides the Mapping Examples of composite service and with Fig. 4 A-4F.In these examples, E is the E1 data from the first communication interface, and D is the FPDP data from the second communication interface, and F is framing information (time slot 0), and S is signaling information (if applicable words is time slot 16), and X is not used.With time slot, usually with self-defined idle code, do not fill.In Fig. 4 A-4F, the first trip correspondence of each figure is as the DSL mapping of the LTU of first node, and the footline correspondence of each figure is as the DSL mapping of the NTU of Section Point.

Table 1 is the DSL Mapping Examples between two E1 FPDP, and Fig. 4 A illustrates its example time slot allocation.

Table 1

Side	LTU	NTU
			E1 speed	10	7
E1 starts	1	1
			FPDP speed	0	0
FPDP starts	0	0
			DSL speed	12	12

Table 2 is the DSL Mapping Examples between the dual serial FPDP, and Fig. 4 B illustrates its example time slot allocation.

Table 2

Side	LTU	NTU
			E1 speed	0	0
E1 starts	0	0
			FPDP speed	10	7
FPDP starts	0	0
			DSL speed	10	10

Table 3 is that Fig. 4 C illustrates the example time slot allocation at the serial data port of a side (LTU side) and the DSL Mapping Examples between the E1 FPDP of an other side (NTU side).

Table 3

Side	LTU	NTU
			E1 speed	0	7
E1 starts	0	1
			FPDP speed	10	0
FPDP starts	0	0
			DSL speed	10	10

Table 4 is that Fig. 4 D illustrates the example time slot allocation at the E1 FPDP of a side (LTU side) and the DSL Mapping Examples between the dual-port of an other side (NTU side).

Table 4

Side	LTU	NTU
			E1 speed	17	5
E1 starts	1	1
			FPDP speed	0	10
FPDP starts	0	6
			DSL speed	19	19

Table 5 is that Fig. 4 E illustrates the example time slot allocation at the serial data port of a side (LTU side) and the DSL Mapping Examples between the dual-port of an other side (NTU side).

Table 5

Side	LTU	NTU
			E1 speed	0	12
E1 starts	0	1
			FPDP speed	20	8
FPDP starts	0	13
			DSL speed	20	20

Table 6 is the DSL Mapping Examples between two dual-ports, and Fig. 4 F illustrates its example time slot allocation.

Table 6

Side	LTU	NTU
			E1 speed	17	13
E1 starts	1	1
			FPDP speed	10	10
FPDP starts	19	14
			DSL speed	29	29

Conclusion

At this, LTU Line Termination Unit has been described to have for accepting the dual-port of two kinds of dissimilar communication services.Each embodiment sends when promoting by the speech business of the telecommunication transport system such as DSL (digital subscriber line) system, serial data business and packing data business.Distribute the bandwidth of telecommunication transport system between different service types, to allow to utilize fully available bandwidth.

Although illustrated and described specific embodiment at this, will be understood by those skilled in the art that, be suitable for realizing that any configuration of identical purpose can substitute shown specific embodiment.Many modifications of the present invention are apparent for those of ordinary skills.Therefore, the application wishes to cover any these type of modifications and variations of the present invention.The present invention wishes only by following claims and equivalents thereof, to be limited obviously.

Claims

1. the terminal unit used in digital line system comprises:

Be suitable for receiving the first communication interface of the first business with first timeslot number, each time slot is corresponding to an incremental bit rate, wherein, for the timeslot number N1 of payload, is less than or equal to the first timeslot number;

Be suitable for the second communication interface of second business that receives, wherein, the bit rate of the second business equals certain times of N2 of described incremental bit rate; With

For being coupled to digital subscriber line and, for the third communication interface of the composite service with second timeslot number is provided, each time slot is corresponding to described incremental bit rate, wherein, the second timeslot number is more than or equal to N1+N2;

Wherein, described terminal unit is suitable for the first to the time slot of composite service the time slot mapping of the first business;

Wherein: described terminal unit is suitable for the second business is mapped to the second portion of the time slot of composite service;

Wherein: the first of described time slot has the timeslot number that is less than or equal to the first timeslot number and is more than or equal to N1.

2. the terminal unit of claim 1, wherein: the first of the time slot of composite service starts from the first time slot place of composite service.

3. the terminal unit of claim 1, wherein: when N1 equals the first timeslot number, the payload of the first business starts from the first time slot place of composite service.

4. the terminal unit of claim 3, wherein: when N1 equals the first timeslot number, the second portion of the time slot of composite service starts from N1+1 time slot place.

5. the terminal unit of claim 2, wherein: when N1 is less than the first timeslot number, the payload of the first business starts from the second time slot place of composite service.

6. the terminal unit of claim 5, wherein: the first time slot of composite service is corresponding to framing information.

7. the terminal unit of claim 1, wherein: the first of described time slot is continuous.

8. the terminal unit of claim 1, wherein: N1 is less than the first timeslot number, and, wherein for an at least N1+1 time slot of the first business, certain time slot of the first business is mapped to the corresponding time slot of the time slot of the first business in composite service.

9. the terminal unit of claim 8, wherein: a time slot of the first business is mapped in composite service a time slot except the corresponding time slot of a described time slot of described the first business.

10. the terminal unit of claim 9, wherein: a described time slot is corresponding to signaling information.

11. the terminal unit of claim 8, wherein: for N1+2 time slot of the first business, the time slot of the first business is mapped to the corresponding time slot of the time slot of the first business described in composite service.

12. the terminal unit of claim 1, wherein: N1 equals the first timeslot number, and, wherein for each time slot of the first business, the time slot of the first business is mapped to the corresponding time slot of the time slot of the first business in composite service.

13. the terminal unit of claim 1, wherein: the first business is the E1 business with 32 time slot 0-31, and wherein the time slot 0 of the first business is corresponding to framing information, and wherein the time slot 16 of the first business corresponding to signaling information.

14. the terminal unit of claim 13, wherein: composite service is the SHDSL business that contains 36 time slot 0-35, when N1 is less than or equal to 30 and while being more than or equal to 15, wherein the time slot 0 of composite service is corresponding to the time slot 0 of the first business, and wherein the time slot 16 of composite service corresponding to the time slot 16 of the first business.

15. the terminal unit of claim 14, wherein: when N1 is less than 15, if N1+N2 is more than or equal to 15, the time slot 16 of composite service is also corresponding to the time slot 16 of the first business.

16. the terminal unit of claim 14, wherein: when N1 is more than or equal to 1, and N1+N2 is less than or equal at 15 o'clock, and the time slot 16 of the first business is corresponding to the time slot N1+N2+1 of composite service.

17. the terminal unit used in digital line system comprises:

Be suitable for receiving pulse code modulation speech business with first timeslot number and or the first communication interface of packing data business, each time slot is corresponding to an incremental bit rate, wherein, for the timeslot number N1 of payload, is less than or equal to the first timeslot number;

Be suitable for receiving the second communication interface of serial data business, wherein, the bit rate of serial data business equals certain times of N2 of described incremental bit rate; With

For being coupled to single-pair high-bit-rate digital subscriber line and, for the third communication interface of the composite service with second timeslot number is provided, each time slot is corresponding to described incremental bit rate, wherein, the second timeslot number is more than or equal to N1+N2;

Wherein, described terminal unit be suitable for the pulse code modulation speech business and or the time slot mapping of packing data business to the first of the time slot of composite service;

Wherein: described terminal unit is suitable for the serial data business is mapped to the second portion of the time slot of composite service;

Wherein: the first of the time slot of composite service has the timeslot number that is less than or equal to the first timeslot number and is more than or equal to N1.

18. the terminal unit of claim 17 also comprises:

Wherein: the first communication interface is interface G.703/704;

Wherein the second communication interface is Nx64Kbps serial data port interface;

Wherein said incremental bit rate is 64Kbps;

Wherein the first timeslot number equals 32, time slot 0-31; And

Wherein the second timeslot number is less than or equal to 36, time slot 0-35.

19. the terminal unit of claim 18, wherein: from by interface V.35, V.36 in interface, group that X.21 interface and RS-530 interface form, select Nx64Kbps serial data port interface.

20. the terminal unit of claim 18 also comprises:

Wherein, described terminal unit be suitable for the pulse code modulation speech business and or the time slot 0 of packing data business be mapped to the time slot 0 of composite service;

Wherein, if N1+N2 is more than or equal to 15, described terminal unit be suitable for the pulse code modulation speech business and or the time slot 16 of packing data business be mapped to the time slot 16 of composite service;

Wherein, if N1+N2 is less than 15, described terminal unit be suitable for the pulse code modulation speech business and or the time slot 16 of packing data business be mapped to the time slot N1+N2+1 of composite service;

Wherein, described terminal unit be suitable for the pulse code modulation speech business and or the remaining time slots of packing data business be mapped to the corresponding time slot of composite service;

Wherein, when N1 is less than 15, described terminal unit is suitable for the serial data business is mapped to the time slot of the composite service that starts from time slot N1+1 place;

Wherein, when N1 is more than or equal to 15, described terminal unit is suitable for the serial data business is mapped to the time slot of the composite service that starts from time slot N1+2 place; And

Wherein, when N1 is less than 15 and N1+N2 while being more than or equal to 15, the time slot 16 of composite service is jumped in the mapping of serial data business.

21. a method of communicating by letter by digital line system comprises:

Reception has the first business of the first timeslot number, and each time slot is corresponding to incremental bit rate, wherein, for the timeslot number N1 of payload, is less than or equal to the first timeslot number;

Receive the second business, wherein, the bit rate of the second business equals certain times of N2 of described incremental bit rate;

Combine the first business and the second business, thereby produce the composite service with second timeslot number, each time slot is corresponding to described incremental bit rate, and wherein the second timeslot number is more than or equal to N1+N2;

First the time slot mapping of the first business to the time slot of composite service;

The second business is mapped to the second portion of the time slot of composite service; And

22. the method for claim 21, wherein: the first of the time slot of composite service starts from the first time slot place of composite service.

23. the method for claim 21, wherein: when N1 equals the first timeslot number, the payload of the first business starts from the first time slot place of composite service.

24. the method for claim 23, wherein: when N1 equals the first timeslot number, the second portion of the time slot of composite service starts from N1+1 time slot place.

25. the method for claim 22, wherein: when N1 is less than the first timeslot number, the payload of the first business starts from the second time slot place of composite service.

26. the method for claim 25, wherein: the first time slot of composite service is corresponding to framing information.

27. the method for claim 21, wherein: the first of described time slot is continuous.

28. the method for claim 21, wherein: N1 is less than the first timeslot number, and, wherein for an at least N1+1 time slot of the first business, certain time slot of the first business is mapped to the corresponding time slot of the time slot of the first business in composite service.

29. the method for claim 28, wherein: a time slot of the first business is mapped in composite service a time slot except the corresponding time slot of a described time slot of described the first business.

30. the method for claim 29, wherein: a time slot of described the first business is corresponding to signaling information.

31. the method for claim 28, wherein: for N1+2 time slot of the first business, the time slot of the first business is mapped to the corresponding time slot of the time slot of the first business described in composite service.

32. the method for claim 21, wherein: N1 equals the first timeslot number, and, wherein for each time slot of the first business, the time slot of the first business is mapped to the corresponding time slot of the time slot of the first business described in composite service.

33. the method for claim 21, wherein: the first business is the E1 business with 32 time slot 0-31, and wherein the time slot 0 of the first business is corresponding to framing information, and wherein the time slot 16 of the first business corresponding to signaling information.

34. the method for claim 33, wherein: composite service is the SHDSL business that contains 36 time slot 0-35, when N1 is less than or equal to 30 and while being more than or equal to 15, wherein the time slot 0 of composite service is corresponding to the time slot 0 of the first business, and wherein the time slot 16 of composite service corresponding to the time slot 16 of the first business.

35. the method for claim 34, wherein: when N1 is less than 15, if N1+N2 is more than or equal to 15, the time slot 16 of composite service is also corresponding to the time slot 16 of the first business.

36. the method for claim 34, wherein: when N1 is more than or equal to 1, and N1+N2 is less than or equal to 15, and the time slot 16 of the first business is corresponding to the time slot N1+N2+1 of composite service.